Re: [PATCH net] net: spacemit: Hold RTNL lock in emac_resume() and emac_suspend()

From: "Troy Mitchell" <troy.mitchell@linux.spacemit.com>
To: "Vadim Fedorenko" <vadim.fedorenko@linux.dev>
Cc: "Breno Leitao" <leitao@debian.org>,
	"Ali Tariq" <alitariq45892@gmail.com>, <netdev@vger.kernel.org>,
	"Andrew Lunn" <andrew+netdev@lunn.ch>,
	"David S. Miller" <davem@davemloft.net>,
	"Eric Dumazet" <edumazet@kernel.org>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Paolo Abeni" <pabeni@redhat.com>, "Yixun Lan" <dlan@kernel.org>,
	"Troy Mitchell" <troy.mitchell@linux.spacemit.com>,
	"Vivian Wang" <wangruikang@iscas.ac.cn>,
	"Chukun Pan" <amadeus@jmu.edu.cn>,
	"Siddharth Vadapalli" <s-vadapalli@ti.com>,
	"Tomas Hlavacek" <tmshlvck@gmail.com>,
	"Muhammad Bilal" <meatuni001@gmail.com>,
	"Maxime Chevallier" <maxime.chevallier@bootlin.com>,
	<linux-riscv@lists.infradead.org>, <spacemit@lists.linux.dev>,
	<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH net] net: spacemit: Hold RTNL lock in emac_resume() and emac_suspend()
Date: Fri, 06 Nov 2026 09:41:31 +0000	[thread overview]
Message-ID: <DMO12HWY5N64.2IJ5XMUKM8WWR@linux.spacemit.com> (raw)
In-Reply-To: <6c36ec6d-5bc8-4ac3-8ad0-79eac7873b67@linux.dev>

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On Thu, 5 Nov 2026 23:28:31 +0100, Vadim Fedorenko wrote:
> > This would work, but I am wondering if it would be possible to call
> > rtnl inside the _open function, when dealing with the PHY? in other
> > words, shrink the time rtnl is held.
>
> +1, especially in emac_open() rtnl is needed only in error path case

emac_open() and emac_stop() are also the driver's .ndo_open and
.ndo_stop, which the core already calls with RTNL held, see
Documentation/networking/netdevices.rst +214. Taking rtnl_lock()
inside them would deadlock on every open and close, so the lock has to
stay in the PM callbacks.

-- 
Troy Mitchell

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